Circuit interrupting device



Dec. 19, 1944. B BAKER 2,365,509

CIRCUIT INTERRUPTING DEVICE Filed Nov. 26, 1941 I5 Sheets-Sheet 2 Dec. 19, 1944.

WITNESSES:

W ZQM E- (3.00 I

B. P. BAKER 2,365,509

CIRCUIT INTERRUPTING DEVICE m VENTOR flan m7! Pfiaielt Patented Dec. 19,

CIRCUIT INTERRUPTING DEVICE Benjamin I. Baker, Turtle Creek, Pa.. asslgnor to .Westinghouse Electric 80 Manufacturing Company, EastPittsburgh, Pa., a corporation of Pennsylvania.

7 Application November 26, 1941, Serial No. 420,515

11 Claims.

The invention relates to circuit interrupting devices of the fluid blast type in which interruption of the circuit is effected by a blast of arc extinguishing fluid forced through the are drawn during circuit interruption.

More specifically, the present invention is concerned with improvements on the fluid blast type of circuit interrupter set forth and claimed in a patent application by Herbert L. Rawlins, Serial No. 212,438, filed June 8, 1938, and issued August 4, 1942, as Patent No.2,292,088, and assigned to the assignee of the present invention. Development work on the type of circuit interrupter described in the aforesaid patent application has disclosed desirable improvement which will be the subject of the present invention.

An object of the present invention is to prevent the re-ignition of the arc extinguished during circuit interruption when a circuit interrupter of the above type is used to interrupt large currents at high voltages.

"Another object of the present invention is to provide a circuit interrupter of the above type wherein the flow of arc extinguishing fluid is for a portion of its length substantially perpendicular to the arc stream, thus creating and maintaining lateral pressure on the arc to force the cross-section of the arc to zero as the current approaches its zero value.

A more sp cific object provide a circuit interrupter of the above type in which the arc restriking distance between the electrodes constantly increases as the opening movement of the circuit interrupter progresses.

Another object of the present invention is to provide a circuit interrupter oi the above type which has a very short arcing time even when of the invention is to Fig. 4 is a sectional view of the circuit interrupter shown in Fig. 3, but shown during the initial portion of the circuit opening operation;

Fig. 5 is a transverse sectional view of the circuit interrupter shown in Fig. 1 taken substantially along the line VV of Fig. 1 and looking in the direction of the arrows; and

Fig. 6 is a transverse sectional view of the circuit interrupter shown in Fig. 3 taken substantially along the line VIVI of Fig. 3 and looking in the direction of the arrows.

Referring to Figs. 1, 2 and 5, there is illustrated a circuit interrupter constructed in accordance with the invention of Herbert L. Rawlins in the .9 and Il. The cap 9 forms one terminal of the used to interrupt large currents at high voltages.

Other objects and advantages will become ap parent from a reading of the following detailed description considered in conjunction with the drawings, in which:

Figure 1 is a sectional view of a circuit'interruptershown in the closed circuit position and containing an embodiment of the present invention;

interrupting device and has a central opening in which is threaded an annular electrode l3. The cap 9 is also provided with a terminal lug I! for connecting the cap 9 and electrode I3 to an external electrical circuit.

The electrode 13 forms a nozzle which communicates with the interior'of thecasing and through which the arc extinguishing gases generated within the casing are expelled, as will be hereinafter described. The electrode l3 has an arcing tip portion H which extends outside of the cap 9, the throat of which is :liared outwardly, as indicated at [9. The electrode I3 is also provided with an annular contact portion 2| which extends insid of the casing I and is adapted to be engaged by a movable contact carried by a movable switch member indicated generally at 23.

A hollow tube 25 of conducting material extends centrally within the casing I, and has one Fig. 2 is a sectional view similar to Fig. 1, but 1 end threaded in a central opening provided in the cap II. A fixed electrode 24 is threaded in the opp site or upper end of the fixed conducting tube 25, and this electrode has a rounded nose 21 which projects partially into the throat 29 of the nozzle or electrode [3.

The movable switch member 23 comprises awhich evolves an arc extinguishing gas when subjected to the heat of an arc. The upper end of the conducting sleeve 3| has a ring-shaped the interrupting device.

conducting sleeve 3| carries a second movable 2 aseaeos movable contact 35 threaded thereon which is movable by the switch member 23 into and out of engagement with the contact portion 2| the electrode l3 to close and open the circuit through The lower end or the ring-shaped contact 31 which is engageable with a stationary annular contact 39 carried by the casing l. The stationary contact I! is carried by a spider member 4| which is threaded in an outer terminal sleeve 43 which forms the opposite terminal of the interrupting device. The terminal sleeve 43 connects the upper and lower sections of the insulating casing 1 together by threadedly engaging the opposed ends of the two sections. A terminal lug 45 is bolted to the terminal sleeve 43, which, together with the terminal lug It, serves to connect the interrupting device in series in the external electrical circuit.

The movable switch member 23 comprising the two movable contacts 35 and 31 which are electrically connected by the tubular conducting sleeve 3|, is mounted for sliding movement on the fixed conducting tube 25, and is connected by a key 41 of conducting material with an operating rod 49 also of conducting material. The operating rod 49 is mounted for sliding movement within the fixed conducting tube 25 and the tube 25 is provided with a pair of elongated slots SI for accommodating the key 4'! and for permitting movement or the switch member by by the axial movement of the switch member 23 and operating rod 49.

In the closed circuit position of the switch shown in Fig. 1, the movablecontacts I! and 31 engage their cooperating stationary contacts 2| and 39, respectively, and the circuit through the device extends from the upper terminal cap.

9 through the stationary contact portion 2|, movable contact 35, conducting sleeve 8|, movable contact 31, stationary contact II, and the spider 4| to the opposite terminal sleeve 43.

To open the circuit interrupter the operating rod 49 is moved downwardly by any suitable op erating mechanism to cause the switch member 23 carrying the movable contacts 35 and 31 to move to the open circuit podtion out of engagement and away from the cooperating stationary contacts 2| and 39. Thus in the open circuit posiiton two gaps in series are introduced in the circuit through the device.

In order to extinguish the arcs drawn, between the pairs of separable contacts, there is provided in the lower section 01 the casing I a stack of annular plates-53 composed 01' an insulating material, such as horn fibre, which evolves an arc extinguishing gas when subjected to the heat or contact 01 an arc. The plates I! are held in position in the lower section or the casing I by means or a ring Iil which clamps the plates together against the cap II to form a solid gasenerating structure. The plates are shaped to provide a tapered annular slot 51 inwhich the are drawn between the movable contact 31 and the stationary contact ll plays, one wall or the slot being tamed by the inner surfaces or the plates It and the opposite wail being formed by the fibre insulating sleeve 33 of the switch member 23 when the switch member 23 is moved downwardly.

The purpose of the tapered shape or the slot 51 is to adapt the device for interrupting currents oi varying magnitude over a considerable range. By providing a tapered annular slot, arcs of varying current magnitude are caused to intimately engage the walls of the annular slot. Current arcs of large magnitude will engage the enlarged upper end of the annular slot and current arcs of small magnitude will engage the walls of the lower or narrow portion of the slot.-

In order to ensure a more complete and uniform engagement oi the arc .with the walls of the annular tapered slot 51 there is provided an electromagnet 59 which is carried by the spider ll and an additional spider 6|. The electromagnet 50 has a winding 63 which is adapted to be connected in series in the circuit of the two arcs by means of an electrode 65 arranged in the path or the are drawn between the movable contact 31 and the stationary contact 38 and insulated from the stationary contact by a sleeve 61. The electrode 65 is also insulated from the spider 6| '-by an insulating ring 64. One terminal of the winding 63 is connected to the fixed electrode 65 and the opposite terminal thereof is electrically connected to the spider 4| and through the same to the terminal sleeve ll. As soon as the movable contact 31 passes the electrode 65 in its downward opening movement, the arc drawn. between the movable contact 31 and the stationary contact 39 is transferred from the stationary contact 39 to the fixed electrode 65 so that at this point the coil 83 of th magnet 59 is connected in series circuit with the arc and is traversed by the current flowing thro h the interrupting device. The electromagnet 59 when energized serves to rotate the are drawn between the movable contact 31 and the fixed electrode 65 around the annular tapered slot il so that it is caused to intimately engage a large portion or the surface or the walls of the slot.

The annular slot 51 forms a pressure chamber which communicates with the nozzle formed by the electrode I! through openings in the spiders 'spectively, during a circuit opening operation of the arc is loopedup somewhat in the manner so indicated at 0 mm. 2, having one of its terminals on the arcing tip portion II and its other terminaionthenoeelloi'thefinedelectrodell.

. creases theefiectiveness of At this point the current flows through the interrupting device as follows: from the terminal cap 9 through the arcing tip portion I9 of the electrode I3, through the are 69, fixed electrode 24, through the fixed conducting tube 25 and the conducting sleeve 3|, movable contact 31, through another are 1| to the fixed electrode 55 through the winding 63 of the electromagnet 59 and spider 4| to the opposite terminal sleeve 43 of the device. The position of the parts at this stage of the opening operation are illustrated in Fig. 2.

The gases generated in the annular slot 51 are at a very high temperature and for this reason are not well suited for interrupting an arc efflciently, although they are capable of interrupting lower voltages. In order to cool and deionize the gases there is interposed between the pressure i chamber or annular slot 51 and the nozzle I3 a .passing over the cooling surface of the coolin means is absorbed by the tubes 15 so that the gases are cooled and deionized to increase their dielectric or are extinguishing strength before being blasted through the nozzle 13. The heat of the hot gases absorbed by the tubes 15 liberates an additional quantity of gas from the material of the tubes which is at alow enough temperature to materially assist in extinguishing the are drawn in the throat of the nozzle.

The ability of a gas blast type circuit interrupter to interrupt a circuit is largely dependent upon the rate of rise of the recovery voltage. The

higher the rate of rise of the recovery voltage the more diflicult the circuit is to interrupt. In order to reduce the rate of rise of recovery voltage and thus increase the circuit interrupting ability of the device, there may be provided a resistance 11 which is connected at one end to the terminal cap 9 and at its other end to the metal cap H, so as to be shunted across the arc 59 inv the throat of the nozzle of electrode l3. The resistance 11 is connected to the'eleotrode l3 by the conducting material of the terminal cap 9 and to the fixed electrode 24 through the cap II, a flexible conductor 19, operating rod and the fixed conducting tube 25. The resistance very" greatly inthe gas blast through the nozzle in extinguishing the. arc. between the annular electrode l3 and'the fixed electrode 24. The residual current which flows through the resistance 11 in series with the arc 1| following extinction of the are 69 in the nozzle is readily interrupted in the annular slot 51.

During circuit interruption the amount of gas generated by the arc'in the annular slot 51 is proportional to the magnitude of the current flowing through the interrupter. magnitude currents a large quantity of gas is generated so that the circuit will be interrupted when the separable contacts have been separated only a small part of their total distance of separation. In the case of lower currents a greater distance of separation. ofthe contacts is required before a sufficient quantity of gas is generated to extinguish the wait being necessary for the are In the case ofheavy to play in the restricted lower portion of the slot 51 to generate suflicient gas in the case of low magnitude currents. It will be understood, howknown manner.

ever, a smaller quantity of gas is required to extinguish low current arcs; therefore, the device automatically operates to generate the required amount of gas in accordance with the magnitude of the current to be interrupted.

The cooling means 13 may take other forms than the specific structure shown and described. Any suitable form of cooling means may be used which has a. multiplicity of passages or interstices to form a large cooling surface area for cooling the gases.

While the plates of the gas generating structure have been described as being composed of horn fibre, it is to be understood that any suitable material which evolves an arc extinguishing gas or vapor when acted on by an arc may be used in place thereof.

The operating means for moving the operating rod 49 may be similar to any of the various types of operating mechanism which are well known in the art. For example, the operating rod may be biased to open circuit position by a suitable spring and releasably held in closed circuit position by a current responsive trip device such as a fusible element or a current responsive latch means. Provision may also be made for manually or electrically operating the rod 49 if desired.

The operation of the device is briefly as follows:

To interrupt the circuit the operating rod 49 is moved downwardly to cause the movable contacts 35 and 31 carried by the switch member 23 to separate from the cooperating stationary contacts 2| and 39 and draw a plurality of arcs in series, one between'the contacts 2| and 35 and another between the contacts 31 and 39. As sQOn as the contact 31 passes beyond the fixed electrode 55 the are drawn between the contact 31 and the contact 39 leaves the contact 39 and transfers to the fixed electrode 65, causing energization of the electromagnet 59. The magnetic field produced by the electromagnet 59 causes the arc to be rotated in the annular chamber 51 where it engages and heats the walls of the chamber 51- to generate a quantity of arc extinguishing gas. The pressure produced by the arc causes the gas to be blasted up through the tubes 15 of the cooling means 13 and through the are drawn between the movable contact 35 and the stationary contact 2| and out through the nozzle opening. The initial blast of gas through the arc drawn between the contacts 2| and 35 moves the are up into the throat 29 of the electrode l3 with one of its terminals on the arcing tip portion I! of the electrode l3 and its other terminal on the fixed electrode 24 as illustrated in Fig. 2. The blast of cooled arc extinguishing-gas through the arc in the nozzle quickly extinguishes the same in a well known manner. The are drawn between the movable contact 31 and the electrode which is connected in series with the resistance 11 following extinction of the arc 69 in the nozzle is quickly extinguished in the annular slot 51 in a well To reclose the circuit interrupter the operating rod 49 is moved upwardly to cause the movable contacts 35 and 31 carried by the switch member 23 to move into engagement with their cooperating stationary contacts 2i and 39.

pletely described and claimed in the aforesaid patent application.

I have discovered that when the above-described circuit breaker is used under some conditions to interrupt large currents at high voltages there 'is a tendency, when an all-metal nozzle is is used, toward long arcing tim as a result of the arc restriking after a current zero between the nose 2! and the lower portion of the nozzle l3 nearest the nose 2?. To prevent this reestablishment of the extinguished are after a current zero, I have provided an annular insulating insert 8| This annular insert 8| prevents the are restriking at high voltages, and thus reduces the arcing tim when the interrupter is used to break large currents at high voltages. I have found that if the annular insulating insert 8| is too long, the arc terminal, which played on the stationary contact 2| when the breaker was slightly opened, will not be blown by the initial blast of arc extinguishing gas from the pressure chamber 57 across the annular insert 8| to the arcing tip portion l9. On the other hand, I have found that if the annular insulating insert 8| is too short, the long arcing time obtained when the breaker is used to interrupt large currents at high voltages will not be effectively reduced. The relative size of the insert 8| to the size of the entire breaker, as shown in Figs. 1 and 2, has

been found to be very satisfactory.

The circuit breaker illustrated in Figs. 3, 4 and 6 is similar in basic construction to the Rawlins breaker described above, but it has a number of improvements embodying the present invention. It comprises a two-part casing of insulating material, generally indicated by the reference numeral l, and on the ends of which are threaded a pair of metal caps 83 and II. The cap 83 forms one terminal of the device and has a central opening 85, through which is loosely inserted in the closed circuit position of the breaker a central movable electrode 81. A plurality of radially disposed conducting plates 89 biased inwardly by a ring-shaped helical tension spring 9| serve to electrically connect the cap 83 to the central movable electrode 87 in the closed circuit position of the breaker, as illustrated in Fig. 3. The central movable electrode 81 forms the upper end of a tubular movable conducting member 93 adapted for longitudinal movement axially of the casing l. to open and close the breaker.

integrally formed with the movable tu'bular conducting member 93 is the movable contact 95, which performs the same function as movable contact 31 in the circuit breaker illustrated in Figs. 1, 2 and 5. At the. lower end of the movable tubular conducting member 93 is formed a ring 91 which may be engaged by any suitable form of operating mechanism. The operating mechanism for the breaker is not shown, but it may be of any suitable type. A vent 99 in the lower end of the movable tubular conducting member 93 communicates to the interior of the movable tubular conducting member 93, and thus permits the flow of gas from within the casing to the air surrounding the casing 1 when the cir-' cuit breaker is being opened.

The electromagnet 59, and its method of connection into the circuit throu h the breaker, is identical with that of the el ectromagnet 59 previ- Figs. 1, 2 and 5. The cooling means 18 is the same as the cooling means previously described An insulating sleeve 38, analogous to the sleeve 33 in Figs. 1, 2 and 5, surrounds the upper portion of the movable tubular conducting member 83, and performs the same function as the sleeve 33 in Figs. 1. 2 and 5. The resistance 11 and its function are the same as resistance 11 previously described in connection with the circuit interrupter illustrated in Figs. 1. 2 and 5.

It will be noted that in the circuit breaker illustrated in Figs. 3, 4 and 6 there is provided an annular insulating insert |0| which changes the direction of flow of the arc extinguishing gases formed both in pressure chamber 51 and in the cooling means 13. Thus, the arc extinguishing gases do not flow substantially longitudinally of the arc stream as in the circuit interrupter illustrated in Figs. 1, 2 and 5; but instead the insulating annular insert ||Il forces the are extinguishing gases to flow substantially perpendicularly into the arc stream, as shown in Fig. 4.

When the circuit interrupter is in the closed circuit position, as shown in Fig. 3, the electrical circuit through the breaker consists of the following: terminal lug l5, upper terminal cap 33, conducting plates 89, movable tubular conducting 1 member 83, movable contact 85, stationary conously described in connection with the circuit breaker illustrated in Figs. 1, 2 and 5. The construction of the gas generating and pressure chamber 51 and its function are the same as in the previously described breaker illustrated in tact 39, spider ll, terminal sleeve 43 to terminal lug 45. When it is desired to open the interrupter, the operating mechanism (not shown) is actuated to pull the ring 81 and hence the movable tubular conducting member 83 downward. During the initial portion of the opening operation or the breaker, two arcs are formed, one are being formed. between the conducting plates 89 and the central electrode 81, and the other are being formed between the stationary contact 39 and the movable contact 85. When movable contact 95 moves below stationary electrode 85, the upper terminal of the second arc is transferred from contact 38 to electrode 85, bringing the electromagnet 59 into the circuit. The initial blast of are extinguishing gas formed in chamber 51 and augmented by the formation of arc extinguishing gas in the cooling chamber 13 transfers the upper terminal of the upper arc from the conducting plates 88 to the arcing region Hi3 of the terminal cap 83 in a manner similar to that described in connection with the circuit breaker illustrated in ,Figs. 1, 2 and 5. Continued downward movement of the movable tubular conducting member 83 increases the distance between the central electrode I! and the arcing region I83 to lengthen the arc stream, and also to initially subject thearc stream to a substantially perpendicular blast of arc extinguishing gas which thereafter changes to a parallel blast of gas. The upper arc is extinguished by this blast of gas, and the lower are which is now in series with the shunting resistance 11, is also broken by the are extinguishing gas formed in pressure chamber 81. There are consequently two air gaps introduced into the circuit through the breaker in the, open circuit position. The full open circuit position of the breaker is not shown in the drawings.

It will be noted in connection with the interrupter illustrated in Figs. 3, 4 and 6 that the central electrode 81 moves away from the upper terminal cap 83 during the opening operation of the interrupter, thus lengthening the arc stream and also increasing the arc restriking distance.

opening operation when the central electrode 81 has just separated from the conducting plates 89, the position of the central electrode 81 in the annular insulating insert IIlI is such as to cause the arc extinguishing gas formed in chamber 51 and cooling chamber 13 to flow upward substantially longitudinally of the arc stream to force a transfer of the upper arc terminal from the conducting plates 89 to the arcing region I03 or terminal cap 83. When, however, the central electrode 81 has moveddown past the annular insulating insert IIII, the flow of gas below the insert II is substantially perpendicular to the arc stream, as shown in Fig. 4, and thus maintains the pressure on the last little thread of are just preceding a current zero.

Since the gas flow is substantially perpendicular to the arc stream, and since the gas flows out of the casing I through the opening 85 in terminal can 83 and through the tubular member 93, both of which are substantially parallel to the arc stream, all the kinetic energy of the gas is given up near point A, thereby increasing the lateral pressure on the are at this point and forcing the cross-section of the are at this point to zero as the current approaches its zero value. Point A,'therefore, represents the region of most rapid gain in dielectric, and from this point fresh gas continuously sweeps the residual ionization back in the direction of the arc terminals I03 and 81, and hence out of the interrupter. Any thermal ionic emission from the arcing region I03 the hot central electrode 81 should not be permitted to enter the region near point A to prolong the arcing. The opening through the tubular movable conducting member 93 permits the fresh gas to sweep the thermal ionic emission and the heat from the central electrode 81 awayfrom region A and out of the breaker casing 1.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details thereof may be made without departing from the spirit of the invention. It is desired, therefore, that the appended claims be given the broadest reasonable interpretation permissible in view of the prior art.

I claim as my invention:

trode 81, and hence thermal ionic emission from .40

1. In a circuit interrupter, a. pair of fixed electrodes one being annularly shaped and the other projecting into the throat of said. annularlyshaped electrode and spaced therefrom, an annular insulating member positioned within said annular electrode at a place which is at a shorter distance to the other electrode than is any part of said annular electrode, means for establishing an are between said fixed electrodes, means sulating member positioned within the throat of said annular electrode, means for generating arc extinguishing fluid under pressure in said pressure chamber, said are extinguishing fluid lengthening the are drawn between said electrodes during the circuit opening operation of the interrupter and finally extinguishing said lengthened arc, said annular insulating member helping to prevent the restriking between the two electrodes of the arc after the lengthened arc has been extinguished.

3. In a circuit interrupter, a casing having an annular electrode forming a nozzle and having a pressure chamber communicating with said nozzle, 9. fixed electrode in said casing projecting into the throat of said annular electrode and spaced therefrom, an annular insulating insert positioned within the throat of said annular electrode so as to be nearest the flxedelectrode, means providing fluid under pressure within said chamber, means for establishing an arc between said electrodes during the opening operation of said interrupter, means -for lengthening said drawn arc by causing one terminal thereof to jump across said insertand for extinguishing the same, said annular insulating insert increasing the restriking distance between said two electrodes after the lengthened arc has been extinguished.

4. In a circuit interrupter, a casing havin an annular electrode forming a nozzle and having a pressure chamber communicating with said nozzle, afixed electrode positioned within said casing projecting into the throat of said annular electrode and spaced therefrom, means for providing fluid pressure in said chamber, an annular insulating member positioned in said annular-electrode between it and said fixed electrode,

movable contact means for bridging said electrodes, said movable contact means causing an arc to form with one terminal of the are on en said are by causing one terminal thereof to .jump across said insulating member and to extinguish said lengthened arc, said annular insulating member. helping to prevent a restriking of the extinguished lengthened are between said two electrodes.

5. In a circuit interrupting device, a casing having an annular electrode forming a, nozzle and a pressure chamber communicating with said nozzle, a movable electrode projecting into the, throat of said annular electrode and making contact'therewith in the closed circuit position of the interrupting device, means for drawing a lurality of arcs in series one between the annular and movable electrodes'and another in said chamber, means in said pressure chamber acted on by the arc therein for developing a fluid under pressure, said fluid being blasted through the arc in said nozzle to extinguish the same, and means for directing the fluid blastinitially substantially longitudinally of the arc stream between said movable and said annular electrodes and for directing the fluid blast substantially perpendicularly to the arc during the final portion of the opening operation of the interrupter.

6. In a circuit interrupter, a casing having an annular electrode forming a nozzle and a pressure chamber communicating with said nozzle, said nozzle havinga contacting portion and an arcing portion, a movable electrode engageable with said contacting portion in the closed circuit position, means for drawing a plurality of arcs one between said annular and said movable electrodes and another in said pressure chamber, means in said pressure chamber acted on by said are formed in the pressure chamber for causing a blast of fluid through said are in the nozale to extinguish the same, means for directing said blast during the initial part of the opening operation of the interrupter substantially longitudinally of said arc in the nozzle to lengthen the same by moving one terminal thereof from said contacting-portion to said arcing portion,

and means for directing said blast during the latter: part oi the opening operation of the interrupter substantially perpendicular to said arc is; the nozzle to eflect the extinguishment there- "7: In a circuit interrupter, a casing having an annular electrode forming a nozzle, a second nozzle formed of insulating material within said casing and spaced from said annular electrode and having the opening thereof of larger crosssection than the opening in said annular electrode, a pressure chamber communicating with both said nozzles, a movable electrode which passes through said insulating nozzle to engage said annular electrode in the closed circuit position, means for drawing a plurality of arcs one between said annular and said movable electrodes and another in said pressure'chamber. means in said pressure chamber acted on by said are formed in the pressure chamber for causing a blast of fluid through said are in the nozzle to extinguish the same, said insulating'nozzle and said movable electrode cooperating.so that a,sos,soo

first transfers the are between said me contact and said movable electrode to said annular electrode and said movable electrode during the initial portion of the circuit opening operation and then eflects an extinguishment of the transferred are between said movable electrode and said annular electrode during the final portion of the circuit opening operation, said insulating nozzle directing the final extinguishing blast substantially perpendicularly to the are stream.

10. In a circuit interrupter, a casing having an annular electrode forming a nozzle, a second nozzle formed of insulating material disposed within said casing and spaced from said annular electrode, a fixed contact disposed between said two nozzles, a movable tubular electrode which ,passes through said insulating nozzle to engage said fixed contact in the closed circuitposition', a pressure chamber, means for drawing a plurality of arcs one between said fixed contact and said movable electrode and another in said pressure chamber, means in said pressure chamber acted on by. said are drawn in said chamber for causing a blast of fluid through said two nozzles which first transfers the are between said fixed contact and said movable electrode to said annular electrode and said movable electrode during the initial portion of the circuit openins operation and then effects the extinguishment of the transferred arc during the final portion of the circuit opening operation, said insulating nozzle having such a configuration that it directs the blast initially substantially 101181- the extinguishing blast of fluid first lengthens I said pressure chamber acted on by the are drawn within said chamber for causing a blast of fluid through said arc in the nozzle to extinguish the same, said insulating nozzle directing the fluid blast substantially perpendicularly to the arc stream in the nozzle during the final portion of the opening operation of the interrupter, said tubular movable electrode discharging out of said casing fluid which has been acted upon by the arc drawn in the nozzle.

9. In a circuit interrupter, a casing having an annular electrod forming a nozzle, a second nozzle formed of insulating material disposed within said casing and spaced from said annular electrode, a fixed contact disposed between said two nozzles, a movable electrode which passes through said insulating noule to engage said fixed contact in the closed circuit position, a pressure chamber, means for drawing a plurality of arcs one between said fixed contact and said movable electrode and another in said pressure chamber, means in said pressure chamber acted on bysaid are drawn in said chamber for causinsa blast of fluid through said two nozzles which tudinall of the arc stream to eflect'the transfer thereof and then later directs the blast substantially perpendicularly of the transferred are said tubular movable electrode discharging out of said casing fluid which has been subjected to the arc.

11. In a circuit interrupter, a casing having an annular electrode forming a nozzle, a second nozzle formed of insulating material disposed within said casing and spaced from said annular electrode, a fixed contact disposed between sa d two nozzles, a movable tubular electrode which passes through said insulating nozzle to engage said fixed contact in the closed circuit position, a pressure chamber, means for drawing a pm rality of arcs one between said fixed contact and said movable electrode and another in said pressurechamber, means in said pressure chamber acted on by said are drawn therein for causing a blast of fiuid through said two nozzles which first transfers the are between said fixed contact and said movable electrode to said annular electrode and said movable electrode during the initial portionof the circuit opening operation of the interrupter and then eilects the extinguishment of the transferred arc during the final portionof the circuit opening operation,

said insulating nozzle having such a confi uration that it directs the blast initially substantially longitudinally of the arc stream to elect the transfer thereof and then later directs the blast substantially perpendicularly of the transferred arc. said tubular movable electrode dischargingv out of said casing fluid which has been subjected to' them, a resistance shunting said annular and said movable electrodes and in series with the arc in said chamber ior'aidins in thecomplete extinction of said are in said nozzle, and meansfor extinguishing said'arcfin said chamber for interrupting said resistance circuit.

BENJAMIN P. BAKER. 

